高 LET 和低 LET 辐射体外诱发细胞恶性转化的比较

目的本研究采用体外细胞转化系统，比较观察了高ＬＥＴ（２３８Ｐｕα粒子，５．２５ＭｅＶ）和低ＬＥＴ（Ｘ射线，１８０ｋＶ）辐射体外诱发成年大鼠肺成纤维细胞系（ＷＡＬ－Ｆ１）恶性转化的特点。方法①应用体外细胞转化模型；②观察指标包括转化细胞形态学和生物学特性的改变；③转化细胞在体内的致瘤作用等。结果α粒子和Ｘ射线诱发同一细胞系转化的形态学与生物学特性基本相似，但在生物学效应上二者存在以下的差异：①细胞存活曲线模型，α粒子为单击单靶模型，Ｄ０值为０．１７２Ｇｙ；Ｘ射线为单击多靶模型，Ｄ０值为１．６６Ｇｙ；②对细胞增殖能力、染色体畸变及集落形成率的影响，产生相近的生物效应所需的剂量，α粒子比Ｘ射线约低１０倍；③以在动物体内致瘤性为终点，引发肿瘤的剂量，α粒子对Ｘ射线的ＲＢＥ值为６（３．０／０．５）。结论实验表明，高ＬＥＴ对体外细胞亦具有较高的致瘤效应。

Comparison of malignant transformation of cells vitro induced by high LET and low LET radiations

Objective To compare the characteristics of malignant transoformation of the adult Wistar rat lung fibroblast cell line (WAL F 1) in vitro induced by high LET ( 238 Pu alpha particles,5 25 MeV) and low LET (X rays 180 kV) radiations. Methods A model of cell transformation in vitro was used;the changes of morphological and biological characteristics of transformed cell induced by two types of radiations were observed;the carcinogenesis of transformed cells in vivo was studied. Results The results showed that the morphological and biological characteristics of transformed cells were basically similar.However,there were some differences between biological effects of cell transformation induced by these radiation types:(1) The model of cell surviving curve for alpha particles was a single hit and single target model with a D 0 value of 0 172 Gy,while that for X rays was a single hit and multi target model with a D 0 value of 1 66 Gy;(2) the iso effect dose of proliferative ability,chromosome aberration rate,and colony forming rate for X rays were 10 times higher than these for alpha particles;(3) the latent period of cell transformation for alpha particles was delayed about 4 5 passages as compared with that for X rays;and (4) the relative biological effectiveness (RBE) for alpha particles versus X rays was approximately 6.0 at an alpha dose of 0.5 Gy. Conclusion The results suggest that the high LET radiation showed higher carcinogenic effect in vitro on cells than low LET radiation did.